Electric utility segment - Consolidating statement of cash flows (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities
Net income	$ 44,601	$ 35,491	$ 77,426	$ 67,830
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment			97,148	91,731
Other amortization			4,840	4,792
Deferred income taxes			21,738	(4,463)
Allowance for equity funds used during construction	(1,997)	(1,896)	(3,736)	(3,309)
Change in cash overdraft			0	193
Other			2,982	1,777
Changes in assets and liabilities
Decrease in fuel oil stock			9,644	(2,362)
Increase in regulatory assets			(11,752)	(19,976)
Change in prepaid and accrued income and utility revenue taxes			622	(4,390)
Increase in defined benefit pension and other postretirement benefit plans liability			95	218
Net cash provided by operating activities			225,460	168,372
Cash flows from investing activities
Capital expenditures			(203,631)	(206,816)
Contributions in aid of construction			16,810	19,089
Other			1,106	3,819
Net cash used in investing activities			(384,986)	(291,775)
Cash flows from financing activities
Common stock dividends			(55,591)	(65,140)
Net increase in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less			12,922	5,571
Other			563	246
Net cash provided by financing activities			116,256	248,548
Net increase (decrease) in cash and cash equivalents			(43,270)	125,145
Hawaiian Electric Company
Cash flows from operating activities
Net income	36,127	33,111	61,764	60,255
Adjustments to reconcile net income to net cash provided by operating activities
Equity in earnings of subsidiaries			(18,862)	(17,366)
Common stock dividends received from subsidiaries			13,184	12,647
Depreciation of property, plant and equipment			63,044	58,778
Other amortization			1,919	1,177
Deferred income taxes			23,954	26,423
Change in tax credits, net			2,772	3,803
Allowance for equity funds used during construction	(1,559)	(1,581)	(2,965)	(2,704)
Other			(1,389)	1,405
Changes in assets and liabilities
Decrease in accounts receivable			14,177	13,651
Decrease (increase) in accrued unbilled revenues			(2,941)	22,907
Decrease in fuel oil stock			6,015	(11,195)
Increase in materials and supplies			(1,748)	297
Increase in regulatory assets			(3,974)	(15,984)
Increase (decrease) in accounts payable			17,150	(5,098)
Change in prepaid and accrued income and utility revenue taxes			(21,371)	(53,350)
Increase in defined benefit pension and other postretirement benefit plans liability			299	0
Change in other assets and liabilities			(11,803)	(7,838)
Net cash provided by operating activities			139,225	87,808
Cash flows from investing activities
Capital expenditures			(152,283)	(154,727)
Contributions in aid of construction			12,824	16,628
Other			132	334
Advances from affiliates			0	(2,100)
Net cash used in investing activities			(139,327)	(139,865)
Cash flows from financing activities
Common stock dividends			(46,800)	(45,203)
Preferred stock dividends of Hawaiian Electric and subsidiaries			(540)	(540)
Net increase in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less			50,995	88,993
Other			8	(216)
Net cash provided by financing activities			3,663	43,034
Net increase (decrease) in cash and cash equivalents			3,561	(9,023)
Cash and cash equivalents, beginning of period			16,281	12,416
Cash and cash equivalents, end of period	19,842	3,393	19,842	3,393
HELCO
Cash flows from operating activities
Net income	5,353	4,617	9,449	8,539
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment			18,898	18,625
Other amortization			911	870
Deferred income taxes			2,538	1,376
Change in tax credits, net			1,913	399
Allowance for equity funds used during construction	(206)	(165)	(333)	(310)
Other			(302)	351
Changes in assets and liabilities
Decrease in accounts receivable			2,007	(787)
Decrease (increase) in accrued unbilled revenues			634	2,154
Decrease in fuel oil stock			924	5,450
Increase in materials and supplies			(708)	(508)
Increase in regulatory assets			2,138	(2,987)
Increase (decrease) in accounts payable			208	(1,411)
Change in prepaid and accrued income and utility revenue taxes			(192)	(3,079)
Increase in defined benefit pension and other postretirement benefit plans liability			27	0
Change in other assets and liabilities			11	(2,199)
Net cash provided by operating activities			38,123	26,483
Cash flows from investing activities
Capital expenditures			(27,436)	(25,106)
Contributions in aid of construction			1,605	1,465
Other			169	124
Advances from affiliates			(3,000)	0
Net cash used in investing activities			(28,662)	(23,517)
Cash flows from financing activities
Common stock dividends			(6,604)	(5,010)
Preferred stock dividends of Hawaiian Electric and subsidiaries			(267)	(267)
Net increase in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less			0	2,500
Other			(8)	0
Net cash provided by financing activities			(6,879)	(2,777)
Net increase (decrease) in cash and cash equivalents			2,582	189
Cash and cash equivalents, beginning of period			2,682	612
Cash and cash equivalents, end of period	5,264	801	5,264	801
Maui Electric
Cash flows from operating activities
Net income	5,759	5,236	9,821	9,235
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment			11,599	11,081
Other amortization			963	1,173
Deferred income taxes			5,623	5,521
Change in tax credits, net			319	259
Allowance for equity funds used during construction	(232)	(150)	(438)	(295)
Change in cash overdraft				193
Other			(331)	21
Changes in assets and liabilities
Decrease in accounts receivable			729	2,377
Decrease (increase) in accrued unbilled revenues			(908)	2,869
Decrease in fuel oil stock			2,705	3,383
Increase in materials and supplies			(26)	106
Increase in regulatory assets			1,159	(1,005)
Increase (decrease) in accounts payable			6,069	2,138
Change in prepaid and accrued income and utility revenue taxes			(6,626)	(7,184)
Increase in defined benefit pension and other postretirement benefit plans liability			(89)	221
Change in other assets and liabilities			(659)	(4,111)
Net cash provided by operating activities			29,910	25,982
Cash flows from investing activities
Capital expenditures			(17,613)	(19,310)
Contributions in aid of construction			2,381	996
Other			30	53
Advances from affiliates			(11,000)	0
Net cash used in investing activities			(26,202)	(18,261)
Cash flows from financing activities
Common stock dividends			(6,530)	(7,587)
Preferred stock dividends of Hawaiian Electric and subsidiaries			(191)	(191)
Net increase in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less			0	(400)
Other			0	(1)
Net cash provided by financing activities			(6,721)	(8,179)
Net increase (decrease) in cash and cash equivalents			(3,013)	(458)
Cash and cash equivalents, beginning of period			5,385	633
Cash and cash equivalents, end of period	2,372	175	2,372	175
Other subsidiaries
Cash flows from operating activities
Net income	0	0	0	0
Changes in assets and liabilities
Net cash provided by operating activities			0	0
Cash flows from investing activities
Capital expenditures			0	0
Contributions in aid of construction			0	0
Advances from affiliates			0	0
Net cash used in investing activities			0	0
Cash flows from financing activities
Net increase (decrease) in cash and cash equivalents			0	0
Cash and cash equivalents, beginning of period			101	101
Cash and cash equivalents, end of period	101	101	101	101
Consolidating adjustments
Cash flows from operating activities
Net income	(10,883)	(9,624)	(18,812)	(17,316)
Adjustments to reconcile net income to net cash provided by operating activities
Equity in earnings of subsidiaries			18,812	17,316
Common stock dividends received from subsidiaries			(13,134)	(12,597)
Deferred income taxes			3
Changes in assets and liabilities
Decrease in accounts receivable			(231)	1,714
Change in prepaid and accrued income and utility revenue taxes			(3)
Change in other assets and liabilities			231	(1,714)
Net cash provided by operating activities			(13,134)	(12,597)
Cash flows from investing activities
Capital expenditures			0	0
Contributions in aid of construction			0	0
Advances from affiliates			14,000	2,100
Net cash used in investing activities			14,000	2,100
Cash flows from financing activities
Common stock dividends			13,134	12,597
Net increase in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less			(14,000)	(2,100)
Net cash provided by financing activities			(866)	10,497
Net increase (decrease) in cash and cash equivalents			0	0
Cash and cash equivalents, beginning of period			0	0
Cash and cash equivalents, end of period	0	0	0	0
Hawaiian Electric Company, Inc. and Subsidiaries
Cash flows from operating activities
Net income	36,356	33,340	62,222	60,713
Adjustments to reconcile net income to net cash provided by operating activities
Equity in earnings of subsidiaries			(50)	(50)
Common stock dividends received from subsidiaries			50	50
Depreciation of property, plant and equipment			93,541	88,484
Other amortization			3,793	3,220
Deferred income taxes			32,118	33,320
Change in tax credits, net			5,004	4,461
Allowance for equity funds used during construction	(1,997)	(1,896)	(3,736)	(3,309)
Change in cash overdraft			0	193
Other			(2,022)	1,777
Changes in assets and liabilities
Decrease in accounts receivable			16,682	16,955
Decrease (increase) in accrued unbilled revenues			(3,215)	27,930
Decrease in fuel oil stock			9,644	(2,362)
Increase in materials and supplies			(2,482)	(105)
Increase in regulatory assets			(677)	(19,976)
Increase (decrease) in accounts payable			23,427	(4,371)
Change in prepaid and accrued income and utility revenue taxes			(28,192)	(63,613)
Increase in defined benefit pension and other postretirement benefit plans liability			237	221
Change in other assets and liabilities			(12,220)	(15,862)
Net cash provided by operating activities			194,124	127,676
Cash flows from investing activities
Capital expenditures			(197,332)	(199,143)
Contributions in aid of construction			16,810	19,089
Other			331	511
Advances from affiliates			0	0
Net cash used in investing activities			(180,191)	(179,543)
Cash flows from financing activities
Common stock dividends			(46,800)	(45,203)
Preferred stock dividends of Hawaiian Electric and subsidiaries			(998)	(998)
Net increase in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less			36,995	88,993
Other			0	(217)
Net cash provided by financing activities			(10,803)	42,575
Net increase (decrease) in cash and cash equivalents			3,130	(9,292)
Cash and cash equivalents, beginning of period			24,449	13,762
Cash and cash equivalents, end of period	$ 27,579	$ 4,470	$ 27,579	$ 4,470